Problem statement

We see warnings in Evergreen telemetry logging about the following:

{
level: WARNING, 
message: Failed Jenkins SSE Gateway configuration request. Unknown SSE event dispatcher jenkins-blueocean-core-js-1539077847900-uelbb, 
name: org.jenkinsci.plugins.ssegateway.SubscriptionConfigQueue, 
timestamp: 1539098203899, 
version: 1
}

https://sentry.io/jenkins-infra/evergreen/issues/698714976/

Expected behavior

I guess that log could inform a bit more on what the issue is, and what the cause can be. How do we fix it?
Is this an actual issue, or more some log spam whose level should be lowered to INFO or less?

Thanks!